====== Convert bind9 zone configuration to a hosts file ======

During migration it's sometimes useful to test a server with many virtual hosts before directing them to their new IP. For this purpose it's necessary to have a proper hosts file on the testing station. The following bash/awk script reads and parses bind9 configuration from an [[http://www.openvz.org|OpenVZ]] virtualized ROOT directory (can be substituted as ''/'' for non-virtualized environments), then converts zone A records to a suitable hosts file format (IPADDR FQDN). The output can be then copied into ''/etc/hosts'' or ''C:\WINDOWS\SYSTEM32\DRIVERS\ETC\HOSTS'' files respectively.

<code bash>
#!/bin/bash

ROOT=/var/lib/vz/root/1000/
bindconf=$ROOT/etc/bind/named.conf
OLDIP=1.2.3.4
NEWIP=5.6.7.8

dumpbindconf() {

    awk -v ROOT=$ROOT '
    {rinclude($0)}
    function rinclude(line,x,a) {
         sub(/^#/,"",line);      # strip leading comments
         split(line,a,/ /);
         if ( a[1] ~ /^[ ]*include/ ) { #looking for =include at start of line
           file=ROOT a[2]
           gsub(/[\";]/,"",file)
           print ";------ INCLUDE " file
           while ( ( getline x < file ) > 0) rinclude(x);.
           close(a[2])}
         else {print line}
    }
'
}

dumpzones() {

    awk -v ROOT=$ROOT '

    /^[ ]*zone/ {.
        zone=$2
        gsub(/[\";]/,"",zone)
    }

    /^[ \t]*file/ {
        file=$2
        gsub(/[\";]/,"",file)
        file=ROOT file
        print "; zone file for " zone
        gethosts(file)
    }

    function gethosts(file) {
        while ( ( getline x < file ) > 0 ) print x;
        close(file)
    }

'

}

dumptohosts() {

    awk '

    /^; zone file for/ {.
        zone=$5
        gsub(/[\";]/,"",zone)
        #print zone
    }

    /^.*@.*IN.*A.*[0-9]+/ {
        print $4 " " zone
    }

    /^[^@]*IN.*A.*[0-9]+/ {
        print $4 " " $1 "." zone
    }

    '

}

cat "$bindconf" | dumpbindconf | dumpzones | dumptohosts | grep "$OLDIP" | sed "s/$OLDIP/$NEWIP/g"

</code>

{{tag>bash bind dns hosts util}}

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